A few months ago i was with 2 other women and their kids. One had a newborn, one a 12month old. I was there with my 4yo and my newborn. My older DD was LOVING the bigger baby, and playing with her a lot. I watched her carefully whenever they were close together, and gave her constant gentle direction (she can tend to be rough sometimes). The two of them were having a great time.
A bit later my DD was over by the window, nowhere near the baby, and i was sat nursing my nb, when the 12month old's mama suddenly said "NO!" very loudly and then shot a really guilty look at me. My DD was stood by the window with a rubber band hooked over her thumb, stretched and ready to ping right at her DD's face. Because they weren't standing close together i just wasn't paying very much attention and another second and her baby could have been rubber-banded in the face. The other mum was soooooo apologetic and i had to tell her about 20 times, no *I* was sorry, and she was completely right to do what she did and stop my DD in her tracks - 4 is old enough to know not to do that but unfortunately maybe not old enough to think about what would happen if you DO do it. My DD tends to learn not to do things AFTER they've been done to her...
To me it was a non-issue, or if anything, a positive thing where i felt supported in my role. She didn't do anything i wouldn't have done and i appreciated the help as it meant i could nurse my newborn and not be constantly panicking about my 4yo- knowing that the other moms were on it too.
OP i think maybe the other mom wanted YOU to do more about it. My DD1 is incredibly high needs and spirited and if i let her she too would be crawling all over the room and annoying people. I don't let her. There isn't really any reason for a child of 4 to be crawling under the table people are eating at. Perhaps the other mom worked HARD to get her boy to sit and eat at the table and doesn't appreciate your DD running riot?
Believe me, i know how hard it is to have the spirited child, but i just think if *I* don't help DD to behave really well i'm doing HER a disservice, after all, the reality is people probably WON'T take it up with me if she behaves badly, they will go straight to telling her off.
Table manners especially have been hard for my DD, she finds it so hard to sit still and control her waving arms and so on!
But we practice at every meal in my house and she is getting there.